In vitro culturing of cells provides material necessary for research in pharmacology, physiology, and toxicology. The environmental conditions created for cultured cells should resemble as closely as possible the conditions experienced by the cells in vivo. An exemplary flask inclusive of a suitable environment for culturing cells is a common laboratory flask. The cells attach to and grow on the bottom surface(s) of the flask, immersed in a suitable sustaining media. With the advent of cell-based high throughput applications, cell culture vessels have been developed to provide an increased surface area for cell growth while also providing necessary gas exchange. These systems employ traditional cell culture vessels including common flasks, roller bottles, cell culture dishes, and multi-layered cell growth vessels. In addition, automation permits manipulation of the cell culture vessel much like that performed by the manual operator.
Even further, flask volumes having multiple layers of cell growth are capable of producing a greater cell yield than commonly known flasks that permit growth of cells on a single bottom wall. The multiple layers may permit gas exchange at a surface of cell attachment or an alternate surface, therefore alleviating the need for head space above the cell growth media. In some flasks, particularly those with multiple layers and/or flasks designed to be completely filled with media, the presence of any air or gas above the liquid media is detrimental to cell growth within the tracheal flask. In particular, a bubble or gaseous material above the media or cells prevents the cells from obtaining necessary nutrients for cellular growth. In addition, the bubble occupies the space between the layers restricting gaseous exchange and the equilibration of gases (e.g., O2 and CO2) between the cells or media and external environment.
In addition, when a flask is vertical filled with media, residual air remains at the top. However, tilting of the flask on its side (permitting adhesive/attachment-dependent cells to grow on internal surfaces) can allow the residual air to make its way in between the surface layers for cell culture, further impeding cellular growth. Alternatively, overfilling the flask would help to eliminate air/gas bubbles, but would also cause contamination.
There is a need for a cell culture flask that can provide an increased surface area for cell growth while preventing residual air/gaseous material from entering the regions of cellular growth. Additionally, the confinement of extraneous gaseous material in a region of the flask away from cellular growth would permit sufficient exchange of nutrients between the media and the multitude of attachment-dependent cells. It would be beneficial to prevent air or gas bubbles that remain in a top portion of a vessel from entering the areas of cell growth during manipulation of the flask from a vertical filling position to a horizontal cell growth position. Consequently, the desired cell culture flask may also be suitable for use in the performance of high throughput assay applications that commonly employ robotic manipulation.